BelkaCTF #6: Bogus Bill

BelkaCTF #6 is over, the gang of money forgers is all caught. Thank you for being a part of this! Congratulations to the winners:
Student track: its5Q, belkakaka, kiwi
Professional track: sinsa, sm233, teo4n6

đź“„ BelkaCTF #6: Bogus Bill write-up

THE RULES

  • The competition starts on April 5th, 2024 at 3 PM CEST / 1 PM UTC / 9 AM EDT. The password for the CTF image will be revealed on this Information page at 3:00 PM CEST, and challenges will open at 3:00 PM CEST. Do not miss it.
  • You will have 48 hours to solve 18 challenges covering this image, ranging in difficulty from 'Baby' to Hard. The game finishes on April 7th, 2024 at 3:00 PM CEST.
  • Dynamic scoring will be used: the more participants solve a challenge, the lower its point value becomes for everyone who solved it. There is no speed bonus, points are decreased for everyone, including those who already solved the challenge. The winner is the one who scored more points than others did. If two competitors have the same amount of points, the one who reached that amount earlier wins.
  • There will be two separate winners, one among students and another among professionals.
  • Awards for all nominations: the winner gets a nice set of Belkasoft merchandise, first 3 places get winner certificates, and everyone else gets a certificate of participation.

THE IMAGE

BONUS POINTS

There are three opportunities to earn bonus points for this CTF:

  1. Past Participation Bonus: We awarded some points to active participants of the Belkasoft LinkedIn group—those who attempted to guess the CTF name and identified fake bill features. Consequently, you may notice that some players have a non-zero score even at the very beginning of the CTF. This is the reason (and also your motivation to follow Belkasoft LinkedIn for the next bonuses).

    A few important points to note:

    • First, this bonus score alone cannot secure a win in the CTF. If you solve all tasks, your bonus score will be nullified, ensuring the base principle that the victory is determined by who solves all tasks first.
    • Second, this bonus score, however, can contribute towards securing a 2nd or 3rd place.

  2. Mid-Event Social Media Post: Halfway through the event, participants can post their current standings on their LinkedIn account and submit the link to earn a bonus score. This option becomes available 24 hours after the CTF starts. The post must include the hashtags #Belkasoft and #BelkaCTF and must remain live until the end of the CTF. Removing the post after receiving the bonus will result in the bonus being withdrawn.

    Unlike the first bonus, winning with this score is possible.

  3. Final Challenge Social Media Post: After solving all the CTF tasks (or 30 minutes before the CTF concludes), participants can earn the final bonus score by posting a message to LinkedIn or Twitter and submitting the link. The same rules apply: the post must contain the hashtags #Belkasoft and #BelkaCTF, and must remain live until the CTF's conclusion.

GOT A QUESTION?

  • Contact the organizers team in Telegram chat: @belkasoftctf. Remember: questions are accepted in English only and answers are public, thus visible to your competitors.

THE TOOL

  • Some tasks are easier to solve with Belkasoft X. Please download the product at https://belkasoft.com/trial.
  • Make sure to use your business email (your company's one or your university's one for students). The download link will be sent to the specified email.
  • It is also important to put "For BelkaCTF 6" into the comment field.
  • You are advised to always use the latest version, currently it's 2.4.15170

THE HASHTAG AND CREDITS